Effect of positioning on the accuracy of decision making of association football top-class referees and assistant referees during competitive matches   总被引：1，自引：1，他引：0  

J Mallo  PG Frutos  D Juárez  E Navarro 《Journal of sports sciences》2012,30(13):1437-1445

Abstract The aim of this study was to examine the effect of positioning on the correctness of decision making of top-class referees and assistant referees during international games. Match analyses were carried out during the Fédération Internationale de Football Association (FIFA) Confederations Cup 2009 and 380 foul play incidents and 165 offside situations were examined. The error percentage for the referees when indicating the incidents averaged 14%. The lowest error percentage occurred in the central area of the field, where the collaboration of the assistant referee is limited, and was achieved when indicating the incidents from a distance of 11-15?m, whereas this percentage peaked (23%) in the last 15-min match period. The error rate for the assistant referees was 13%. Distance of the assistant referee to the offside line did not have an impact on the quality of the offside decision. The risk of making incorrect decisions was reduced when the assistant referees viewed the offside situations from an angle between 46 and 60°. Incorrect offside decisions occurred twice as often in the second as in the first half of the games. Perceptual-cognitive training sessions specific to the requirements of the game should be implemented in the weekly schedule of football officials to reduce the overall error rate.  相似文献   

Active relatives and health-related physical fitness in European adolescents: The HELENA Study     

M Martín-Matillas  FB Ortega  JR Ruiz  D Martínez-Gómez  G Vicente-Rodríguez  A Marcos  L Béghin  A Kafatos  M González-Gross  M Zaccaria  D Molnár  S De Henauw  M Sjöström  LA Moreno  MJ Castillo On Behalf Of The Helena Study 《Journal of sports sciences》2012,30(13):1329-1335

Abstract High physical fitness in childhood and adolescence is positively associated with favourable health-related outcomes. Our aim was to examine the relationship between relatives' (father, mother, brother, sister, and best friend) physical activity engagement and encouragement on adolescents' physical fitness. Adolescents were part of the HELENA study, a multi-centre study conducted in 10 cities from nine European countries in 2006-2008. Participants were 3288 adolescents (48% boys, 52% girls) aged 12.5-17.5 years with valid data on at least one of the three fitness variables studied: muscular strength (standing long jump), speed/agility (4×10 m shuttle run), and cardiorespiratory fitness (20 m shuttle run). The adolescents reported their relatives' physical activity engagement and encouragement. Analysis of covariance showed that relatives' physical activity engagement (father, mother, brother, and best friend) was positively related to cardiorespiratory fitness (P?相似文献   

The interaction of functional and dysfunctional emotions during balance beam performance     

Cottyn J  De Clercq D  Crombez G  Lenoir M 《Research quarterly for exercise and sport》2012,83(2):300-307

The interaction between functional and dysfunctional emotions, as one of the major tenets of the individual zones of optimal functioning (IZOF) model (Hanin, 2000), was studied in a sport specific setting. Fourteen female gymnasts performed three attempts of a compulsory balance beam routine at three different heights. Heart rate and self-report of functional and dysfunctional emotions were measured during each routine. These data revealed the effectiveness of inducting emotions by manipulating height. Also, performance decreased on the most challenging condition, (i.e., the first attempt on the highest height). Moderated hierarchical regression analysis revealed a significant interaction between functional and dysfunctional emotions only when the dysfunctional emotion level was low.  相似文献   

The effect of warm up on single and intermittent-sprint performance     

Yaicharoen P  Wallman K  Bishop D  Morton A 《Journal of sports sciences》2012,30(8):833-840

Lack of benefit of warm up on prolonged intermittent-sprint performance has been proposed to be due to use of a pacing strategy by participants. To investigate this, twelve participants performed four cycle trials that consisted of either prolonged intermittent-sprint performance (80 min) or single-sprint performance (4 s), with or without a warm up. The first-sprint of intermittent-sprint performance was also assessed. No interaction effects (P > 0.05) were found between trials for intermittent-sprint performance for total work (J · kg(-1)), or percentage work and power decrement. Work done during the first-sprint of intermittent-sprint performance (no warm up) was less (P < 0.001) than the first-sprint of intermittent-sprint performance (warm up; effect size (ES) = 0.59) and both single-sprint trials (warm up and no warm up; ES = 0.91, 0.75, respectively). Peak power (W · kg(-1)) for single-sprint (warm up) was greater (P < 0.05) than single-sprint (no warm up), and the first-sprint of intermittent-sprint performance (warm up and no warm up). Warm up improved single-sprint performance and the first sprint of intermittent-sprint performance. Use of a pacing strategy probably resulted in similar intermittent-sprint performance between trials. These results suggest that team-sport players should perform a warm up at the start of a game or before substitution during a game.  相似文献   

Characterizing the mechanical parameters of forward and backward falls as experienced in snowboarding     

Schmitt KU  Wider D  Michel FI  Brügger O  Gerber H  Denoth J 《Sports biomechanics / International Society of Biomechanics in Sports》2012,11(1):57-72

Wrist injuries are frequently observed after falls in snowboarding. In this study, laboratory experiments mimicking forward and backward falls were analysed. In six different falling scenarios, participants self-initiated falls from a static initial position. Eighteen volunteers conducted a total of 741 trials. Measurements were taken for basic parameters describing the kinematics as well as the biomechanical loading during impact, such as impact force, impact acceleration, and velocity. The effective mass affecting the wrist in a fall also was determined. The elbow angle at impact showed a more extended arm in backward falls compared to forward falls, whereas the wrist angle at impact remained similar in forward and backward falls. The study results suggest a new performance standard for wrist guards, indicating the following parameters to characterize an impact: an effective mass acting on one wrist of 3-5 kg, an impact angle of 75 degrees of the forearm relative to the ground, and an impact velocity of 3 m/s.  相似文献   

Clodronate-containing liposomes attenuate lung injury in rats with severe acute pancreatitis     

Dang SC  Jiang DL  Chen M  Li D  Zhang JX 《Journal of Zhejiang University. Science. B》2010,11(11):828-835

Objectives:Severe acute pancreatitis(SAP) can lead to acute lung injury(ALI) .The purpose of this paper is to investigate the protective effect of clodronate-containing liposomes on ALI in rats with SAP.Methods:The thin film method was used to prepare liposomes.Sprague-Dawley rats were randomly divided into three groups.After the SAP model was established by injecting 5%(w/v) sodium taurocholate(2 ml/kg body weight) into the subcapsular space of the pancreata,normal saline was administered to the control(C) group,phosphate buffer solution(PBS) -containing liposome to the Pgroup,and clodronate-containing liposome to the Tgroup through tail veins.Blood samples were obtained from the superior mesenteric vein at 2 and 6 h to measure the levels of amylase,interleukin-6(IL-6) ,and tumor necrosis factor-α(TNF-α) .Morphological changes in the pancreata and lung were observed using hematoxylin and eosin(HE) staining,while cell apoptosis was detected using terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling(TUNEL) .In addition,the macrophage marker cluster of differentiation 68(CD68) in lung tissue was detected with immunohistochemistry.Results:Blood levels of amylase,IL-6,and TNF-αwere significantly increased in the Pgroup compared to those in the Tgroup(P0.05) .In the Tgroup,large numbers of TUNEL-positive cells were observed,but no or few in the C and Pgroups.Gross inspection and HE staining of pancreata and lung showed dramatic tissue damage,including inflammation and necrosis in the Pgroup.Less remarkable changes were noted in the Tgroup,and the C group exhibited normal histology.The histological scores according to Kaiser's criteria were consistent with HE findings.The number of CD68-positive macrophages decreased in the Tgroup.Conclusions:Clodronate-containing liposomes have a protective effect against ALI in rats with SAP.Blockade of macrophages may represent a novel therapeutic strategy in SAP.  相似文献   

Contemporaneous and longitudinal associations between social behavior and literacy achievement in a sample of low-income elementary school children     

Miles SB  Stipek D 《Child development》2006,77(1):103-117

This study investigates associations between social skills (aggression and prosocial behavior) and literacy achievement in a sample of low-income children (between 4 and 6 years old when the study began) during elementary school. Results revealed consistent associations between social skills and literacy achievement in the first, third, and fifth grades, but the patterns of the associations were different for aggression and prosocial behavior. While the strength of the association between aggression and literacy achievement increased over the elementary grades, the association between prosocial behavior and literacy achievement decreased. In addition, path analyses revealed that poor literacy achievement in the first and third grades predicted relatively high aggressive behavior in the third and fifth grades, respectively.  相似文献   

Demographic characteristics and rates of progress of deaf and hard of hearing persons receiving substance abuse treatment     

Moore D  McAweeney M 《American annals of the deaf》2006,151(5):508-512

A lack of demographic information and data related to the achievement of short-term goals during substance abuse treatment among persons who are deaf or hard of hearing dictated the need for the study. New York State maintains a database on all individuals who participate in treatment. Within this database, 1.8% of persons in treatment for substance use disorder (SUD) were also deaf or hard of hearing. As hypothesized, members of the deaf and hard of hearing sample were older, likelier to be white, and likelier to be female, relative to the SUD-only group. For both groups, alcohol, heroin, and cocaine had the highest rates of reported use. Achievement of short-term goals in the areas of alcohol use, drug use, vocational/educational goals, and overall goals indicated no differences between the deaf and hard of hearing group and the SUD-only group. Implications of these findings are discussed.  相似文献   

Recognizing the face of Johnny, Suzy, and me: insensitivity to the spacing among features at 4 years of age     

Mondloch CJ  Leis A  Maurer D 《Child development》2006,77(1):234-243

Four-year-olds were tested for their ability to use differences in the spacing among features to recognize familiar faces. They were given a storybook depicting multiple views of 2 children. They returned to the laboratory 2 weeks later and used a "magic wand" to play a computer game that tested their ability to recognize the familiarized faces and their own face based on the spacing of features. Children performed at chance levels. Follow-up studies confirmed that they had attended to internal facial features and validated the stimuli. The results contrast with studies showing some sensitivity to the spacing of features in infants and preschool children; multiple mechanisms of face processing may make use of spatial relations and develop at different rates.  相似文献   

Human cancer genetics     

Li M  Albertson D 《Journal of Zhejiang University. Science. B》2006,7(2):164-164

Cancer is a genetic disorder.Although heredi-tary cancers account for only a small fraction of all tumors,most cancers are caused by a variable mix of heredity and environment that leads to accumulations of genetic alterations and then uncontrolled cell pro-liferations(Kops et al.,2005).In addition,genetic alteration is one of the a few most important bio-logical factors that determine the diagnosis and prognosis of different cancers and dictate the treat-ment strategies for cancer patients.Fu…  相似文献